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Background: Current techniques for mapping and ablating cardiac arrhythmias are valuable, but have limitations. We devised a novel method of predicting the origin of a focal arrhythmia wavefront that utilizes conduction velocity (CV), the difference in electrogram timing during arrhythmia (t), and the distance between two points (z) to generate prediction curves which can be applied to an electroanatomic map. The intersection of two such curves predicts the origin of the wavefront., Objective: To describe the rationale behind a novel method of arrhythmia mapping and assess its feasibility in a retrospective study of focal arrhythmias., Methods: We retrospectively studied 12 patients with arrhythmias with focal chamber activation that were successfully mapped and treated with ablation. CV during arrhythmia was measured using electroanatomic mapping software. Values for z and t were calculated for two pairs of points. Two prediction curves were generated and superimposed onto the electroanatomic maps. The distance between the intersection of the two curves and the wavefront origin was recorded. The shortest distance between individual curves and the wavefront origin was also measured., Results: Twenty-four curves were successfully generated in 12 patients. The distance from the intersection of two curves and the wavefront origin was 9.2 ± 7.7 mm. The shortest distance between individual prediction curves and the wavefront origin was 5.2 ± 5.2 mm., Conclusions: Wavefront origins may be predicted by a novel method utilizing a limited number of measurements. Further study of this method requires its integration with an electroanatomical mapping system., (Copyright © 2018. Published by Elsevier Ltd.)

Background: A left ventricular aneurysm (LVA) occurs between 3.5% and 9.4% of all cases of acute myocardial infarction. A fragmented left sided QRS (RSR; pattern or its variant RSr;, rSR;, or rSr;) without evidence of bundle branch block (QRS duration

Standard electrocardiographic criteria for exercise testing require near maximal exertion and fail to detect ischemia in the presence of previous infarction or conduction or repolarization abnormalities, in women, or in the presence of certain drugs. Changes in P-wave morphology have been suggested as having diagnostic utility; however, no specific criteria exist, and it is not clear which changes are most useful. This investigation evaluated the ability to detect the presence of coronary artery disease by examining changes in P-wave morphology during exercise. A group of 123 consecutive patients underwent maximum (symptom-limited) exercise nuclear stress tests. The electrocardiograms at rest, 2 minutes of exercise, 50% of maximum exercise time, maximum exercise, and 3 minutes of recovery were analyzed for the duration of the P wave in lead II, the duration of the terminal negative component of the P wave in lead V1, the amplitude of the terminal negative component of the P wave in lead V1, and the duration of the P wave in lead V5. These variables were then analyzed for their relation to the presence of perfusion defects. Of all the P-wave criteria tested, a change in amplitude of the negative component of the P wave in lead V1 from at rest to 50% of maximum exercise time of <0.025 mV was the most predictive of coronary artery disease.

Objectives: QT dispersion (QTd) measures the variability of the ventricular recovery time. QTd may identify patients at risk for ventricular arrhythmias and sudden cardiac death (SCD). The purpose of our study was to determine the effect of obstructive sleep apnea (OSA) on QTd. Methods: There were 199 patients studied: 101 patients (28 women, 73 men) with OSA diagnosed in our sleep center and 98 patients (49 women, 49 men) without OSA from the outpatient clinic, representing the control group. QT intervals (milliseconds) were measured in each of the 12 leads of a standard surface electrocardiogram during wakefulness and QTd calculated (QTmax - QTmin). QTcd, which corrects for heart rate, was also calculated. Results: Mean age and heart rate were similar in men and women with or without OSA. Control patients exhibited a significant difference (p < 0.001) in QTd between men (48 ± 19) and women (31 ± 13). Men and women with OSA had similar QTd (56 ± 35 vs. 54 ± 21) but higher QTd compared to the control group. QTcd results were similar to QTd. Conclusions: Patients with OSA and no structural heart disease have a higher QTd/QTcd compared to an overtly healthy patient population, possibly serving as a marker for an increased risk of SCD. Copyright © 2011 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Objectives: Although epilepsy may be associated with an increased risk for sudden cardiac death, its effects on Q-T intervals has not been established. Methods: To determine whether changes in Q-T interval duration (QTmax c, QTmin c) and dispersion (QTD c) occur in epileptic patients, we retrospectively studied 40 consecutive patients (age: 36.1 ± 22.2 years) who have had a seizure disorder for 14.0 ± 12.2 years and were seen in the Epilepsy Monitoring Unit, and 60 age-matched non-epileptic controls (age: 38.0 ± 15.6 years). Q-T intervals were calculated from a single 12-lead ECG. Results: QTmax c (425 ± 30 vs. 410 ± 36 ms, p = 0.040) and QTD c (63.1 ± 22.4 vs. 31.0 ± 17.2 ms, p = 0.000) were higher, and QTmin c (362 ± 36 vs. 379 ± 33 ms, p = 0.040) was lower in epilepsy patients. QTmax c was significantly correlated with disease duration (r = –0.35, p = 0.028) before, but not after age correction (r = –0.31, p = 0.053). Neither age nor reported recent seizure frequency was correlated with any repolarization index. Conclusions: QTmax c and QTD c are higher in epilepsy patients as compared to control subjects. While Q-T interval appears to be related to disease duration, particularly over the early history of disease, it is unrelated to patient age or recent reported seizure frequency. Copyright © 2009 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

The QT dispersion (QTd) is a non-invasive means of identifying those patients at an increased risk of developing sudden cardiac death (SCD). Although levofloxacin has a minimal effect on the QTc interval, isolated reports of QT prolongation, polymorphic ventricular tachycardia with a normal QT interval and TdP have been reported. The purpose of this study was to examine the effect of intravenous levofloxacin on the QT interval and QTd. Of the 50 patients who were deemed candidates to receive intravenous levofloxacin, 29 met the eligibility criteria and were enrolled in this study. A 12-lead ECG was performed before the initiation of levofloxacin (baseline), and on days 3 and 5. The QTc min, QTc max and the QTd were calculated. Measurements where made by two independent observers blinded to the patients’ clinical status. The QTd increased significantly on days 3 and 5 following the initiation of therapy [QTd (baseline) 33.3 ± 20 ms, QTd (day 3) 64.4 ± 31.3 ms ( p = 0.023), QTd (day 5) 66.8 ± 20.3 ms, ( p = 0.008)]. The increase in the QTd was significantly longer in men than women. Although women had a shorter baseline QTd compared to men, this did not achieve statistical significance. Intravenous levofloxacin was found to significantly increase the QTd, which was more pronounced in men compared to women. Its effect on the QTd may increase the risk of developing a potentially fatal ventricular arrhythmia. Therefore, care must be taken when prescribing this medication to patients with a pre-existing risk of developing SCD. [ABSTRACT FROM AUTHOR]

Most wide-complex tachycardias encountered in the emergency department (ED) are ventricular in origin, most commonly associated with structural heart disease. Ventricular tachyarrhythmias range in severity from life-threatening rhythms (eg, ventricular fibrillation and hemodynamically compromising ventricular tachycardia [VT]) to idiopathic forms of VT, which have a benign clinical course and a more favorable prognosis. The authors present the case of a 34-year-old woman who presented to the ED, with a wide-complex tachycardia with a rightbundle-branch block (RBBB) morphology and a right inferior axis, which was terminated with adenosine. The patient was previously misdiagnosed as suffering from a paroxysmal supraventricular tachycardia (SVT), which was unresponsive to beta-blocker therapy. Although the tachycardia responded to adenosine, suggestive of an SVT, the patient was referred to the arrhythmia service, where further work-up revealed an uncommon form of an idiopathic VT, originating from the left anterior fascicle. The authors discuss the unique electrocardiographic and electrophysiologic properties and useful diagnostic maneuvers required to properly identify this form of VT. [ABSTRACT FROM AUTHOR]

The objective of this study was to measure the normal variation of QT dispersion (QTd) with respect to age and gender. The QT interval is a measure of the duration of ventricular depolarization and repolarization, while the QTd is a measure of the variability of the ventricular recovery time. The QTd has been suggested as a means of identifying those patients at risk for sustained ventricular tachyarrythmias and sudden cardiac death (SCD). A total of 250 patients (120 women, 130 men; age range 20-86 years) were recruited for this study. The QT intervals were measured in each of the 12 standard leads of the electrocardiogram. Data are presented as mean (μ) ± SD. The QTd did not vary significantly within the same gender. A significant difference (P < 0.001) was noted in QTd between men (age [μ] = 53.3 ± 15.6 years, QTd = 0.044 ± 0.019 s) and women (age [μ] = 52.1 ± 15.1 years, QTd = 0.034 ± 0.015 s). Overall, men had a greater QTd. while women had a longer QT. In conclusion, we found that men had a longer QTd, which may explain the increased risk of SCD. However, women have a longer QT interval with a smaller QTd. A longer QTmin, as opposed to a longer QTmax, is responsible for the shorter QTd in women. This longer QTmin in women may predispose to an increased risk of drug induced torsades de pointes. [ABSTRACT FROM AUTHOR]

The article presents a case study of a woman subjected to a preoperative evaluation before undergoing noncardiac surgery for her uterine fibroid tumor. The resting electrocardiogram (ECG) of the patient manifested sinus arrhythmia with complete heart block (CHB) with a junctional escape rhythm. The researchers note that the case shows the significance of exercise ECG stress testing to patients in CHB to assess their need for an electronic pacemaker or other therapy.